Mapping Seismic Shaking

In sweltering triple-digit heat in the middle of a remote area of the western Mojave Desert, Cal State Fullerton earthquake scientist Sinan Akçiz trekked miles of sandy rugged terrain in a race against the clock. For a period of two weeks, over three separate trips, he combed the land in search of ruptures in the surface following the pair of powerful earthquakes that rocked Ridgecrest over the Fourth of July holiday. His goal was to record evidence before it disappeared beneath a bed of silt.

“We’re trying to map the delicate rupture trace and measure the surface offsets before they quickly deteriorate and disappear,” shares Akçiz, assistant professor of geological sciences. A native of quake-prone Turkey, he has spent years studying California’s famed San Andreas Fault.

Akçiz packed his bags and geology tools, and left for the desert on July 6 as one of several earthquake experts called to the scene to assess the aftermath of the intense seismic shaking. His student, geology major Salena Padilla, an intern at the Southern California Earthquake Center, joined him in the field.

The epicenter of the 7.1 magnitude earthquake that hit Ridgecrest on the evening of July 5 and rattled the nerves of millions of Southern Californians — from Los Angeles to Orange County and beyond — was within the Naval Air Weapons Station China Lake. The military base is 150 miles north of Los Angeles and just northeast of Ridgecrest. A precursor 6.4 magnitude quake first struck the desert community the morning of July 4. Both tremors were the biggest earthquakes to hit Southern California in almost two decades.

Akçiz mapped the southern continuation of the surface rupture south of the military base, collaborating with scientists from the U.S. Geological Survey and the California Geological Survey who had clearance to access the base for mapping the main rupture. Working 12- to 13-hour days, with a tape measure in hand, Akçiz tracked the surface rupture on foot using GPS. He measured surface displacement — where the ground visibly shifts along the fault — on unpaved desert roads, dirt bike tracks and dry creek channels.